Project 25 Technology Information Group

Tuesday, July 23, 2019

Project 25 Technology Information Group

Join PTIG at IWCE in Orlando March 5-8 2018 to get the latest updates and new information on Project 25 Systems, Case Studies, and the P25 Standards.

See us at the PTIG Booth # 2545

  • View the latest, interoperable, P25 products and services
  • Meet with P25 System administrators and practitioners
  • Get Answers for your P25 questions from Industry technical experts and Consulting Groups

Attend PTIG P25 Panels and Sessions

Note: registration fees required by IWCE to attend these sessions  

P25 Foundations:

Monday March 5th **8:30 AM to 11:30 AM** Room N320GH

Offers an overview of the P25 Standards, Interfaces and applications for P25 Conventional and Trunked technologies.  New P25 standards document releases and future work direction will be covered.  The 2018 Focus will be on ISSI/CSSI interoperability between P25 Systems, New Link Layer Encryption and Key fill device standards, P25 for Emergency Communications, and use of P25 in System Procurement and Upgrades.

P25 User Experience:

Monday March 5th **2:30 PM to 5:30 PM **Room N320GH


Offers Project 25 user experiences and P25 system case studies.  It is structured as a series of presentations from a diverse user group including Federal, State and Local government Systems.  Presentations include P25 system description, its scope, capabilities, agencies served, development history, interoperability achieved, issues resolved, and lessons learned.  Governance structure, and revenue sources will be presented as well as costs for user agency participation.  P25 System interface to Public Safety Broad-band data, and migration will be shared.  

Del Smith, Alaska ALMR (Moderator), Cindy Cast, Miami Dade County FL, Brad Stoddard, State of Michigan, John Richards, State of Maine, Keith LaPlant, United States Coast Guard, Jim Downes, DHS OEC, Chief Lorin Mock, Clay County FL, James Miller, Hamilton County IN, John Valarelli, MTA Police, Long Island NY, Allen Wonder, Washington Metropolitan Area Transit Authority, Washington DC, Stephen Nichols, Project 25 Technology Interest Group


P25 Security: New Standards, Applications, Interoperability:

Wednesday March 7th 4:15 PM to 5:30 PM Room N220E

P25 System Security and Encryption has become increasingly important to protect mission critical communications from unauthorized listeners.  The session will cover: P25 Security Standards updates, enhanced sharing between Key management facilities and devices; and a future new P25 Link Layer Encryption standard.  P25 Authentication and AES encryption applications will be detailed.  Proper planning and coordination is essential to maintain effective communications interoperability.  The panel will address guidelines and best practices for Encryption planning and radio programming applications.


P25 System of the Month

Central Indiana Counties

City of Indianapolis, Marion County, Hamilton County, Madison County

Central Indiana Counties Partner to leverage

cost savings and form a regional interoperable

communications network


The Full Whitepaper including system demographics for the 3 Central Indiana P25 Systems can be down loaded using the link below:

P25 System of the Month: Central Indiana Counties

20171214 100332


The three-county system has realized many great benefits from sharing common infrastructure utilizing the P25 architecture.  Previously all three counties were required to maintain radios in their respective Public Safety Answering Points (PSAPs) and create patches to the respective jurisdictions.  Patching proved problematic and unreliable at best.  A great many of the field units did not have direct communications with the neighboring jurisdictions, especially during large or critical events.  This created a First Responder safety issue, which the counties realized needed to be addressed as soon as practical.

Since the counties have upgraded to P25, the three counties now share talkgroups including public works talkgroups to allow for greater efficiency.  The counties have created several mutual aid (MA) talkgroups that can roam across all systems in the event of a disaster or large-scale event like the Super Bowl.

An additional benefit of the three counties upgrading to P25 is the ability to have interoperable communications with the State of Indiana’s P25 system.  This system is utilized by hundreds of agencies throughout Indiana as well as Federal Public Safety partners.  No longer do officers need to have multiple radios available to communicate to these important partners.

Project 25 Technology Interest Group Releases New Whitepaper:

Project 25 Radio Authentication

The paper was authored by:

Jim Holthaus, Vice President, Chief Technical Officer, BK Technologies

Project 25 radio standards now provide a method of authenticating subscriber radios for operation on P25 trunked radio systems.  This paper explores the need for and functionality of P25 Link Layer Authentication services on trunked radio systems.

For decades, public safety communications system operators were protected from unauthorized access through the restrictions that equipment manufacturers placed on radio programming equipment.  So even if an unauthorized individual had radio equipment and programming software, without the so called ‘system key’, programming a radio for an individual radio system was not possible.  In general, this level of protection works quite well for many public safety agencies.  However, the use of the system key is only as reliable as the methods used to protect unauthorized access to such a key. 

As the technological abilities of those wishing to steal service or disrupt public safety communications systems expand, additional measures to protect unauthorized access to public safety communications systems are required.

Public Safety and government radio users, through the Project 25 Standards process have requested inclusion of additional measures to prohibit unauthorized access to P25 systems.  The Project 25 standard provides this protection through the use of authentication technology.  The Project 25 standard defines a challenge/response system that allows the radio system and/or subscriber radio to authenticate itself before service is granted. 

The full whitepaper on P25 Link Layer Authentication can be found using the link below:


Project 25 Radio Authentication

P25 Standards Update from the TIA TR-8 Meetings San Diego Oct 18-19

Andy Davis, Chairman TIA TR-8

This document highlights TR-8 accomplishments and work in progress for 2017.  The document will be updated after every TR-8 face to face meeting occurring in 2017.  After the first 2017 version, each update will use blue font to indicate the updates.



The full report can be accessed using the link below

Updates from the October Meeting:

Completed in 2017:

Air Interfaces

  • An addendum to the Trunking Control Channel Messages standard was approved for publication.

     This addendum introduces a “Vehicle Sensed Emergency” flag to the Emergency Alarm message.

  • An addendum to the Trunking Control Channel Messages standard was approved for ballot.

This addendum introduces an “Accessory Sensed Emergency” flag to the Emergency Alarm message.

Wireline Interfaces

  • An addendum to the ISSI Messages and Procedures for Supplementary Data was approved for ballot.

This addendum introduces the messages and procedures for Individual Regrouping control across an ISSI/CSSI.



  • A revision of the Location Services Overview bulletin was approved for publication.

This revision aligns the content of the Overview document with the content of the Tier 1 and Tier 2 Location Service Specifications.


Work in Progress:

Air Interfaces

  • A revision to the Conventional Interoperability Test standard is in progress

This revision corrects editorial errors and makes clarifications on various test procedures but does not add, remove or technically alter tests. 



Project 25 Technology Interest Group Releases New Whitepaper:

Project 25 Trunking Control Channels

The paper was authored by:

Dominick Arcuri: DVA Consulting

Andy Davis: Chairman TIA TR-8, Senior Resource Manager-Motorola Solutions

The New Project 25 Technology Interest Group Whitepaper defines the use and benefits of the current P25 Frequency Division Multiple Access (FDMA) Trunking Control Channel used in most P25 Trunking Systems today as well as application and benefits of the new, recently released, P25 Time Division Multiple Access (TDMA) Trunking Control Channel.  Planning and User Interoperability considerations required for transition from FDMA to TDMA P25 Trunking Control Channels are also covered.  These include a thorough inventory of the subscriber base and roaming requirements for all agencies supported by the system, including visiting radios from interoperability and roaming partners. 

The P25 suite of standards is evolving and continuing to grow as technology and user requirements evolve.  The standardization of the TDMA control channel will enable multiple manufacturers to support this capability with interoperable equipment.  Additionally, the TDMA control channel will provide another option for system managers and user agencies to effectively support their users and to improve the spectrum efficiency of their network both low density and high density situations. 

A copy of the Full whitepaper can be found on the Project 25 Technology Interest Group Website using the following link:


Whitepaper: P25 Trunking Control Channels



A P25 trunked system can be deployed with either FDMA or TDMA traffic channels or a mixture of FDMA and TDMA traffic channels.  The FDMA Common Air Interface (CAI) is designed to provide 12.5 kHz spectral efficiency and meet FCC (Federal Communications Commission) narrow-banding requirements, while the TDMA CAI is designed to provide 6.25 kHz “equivalent” spectral efficiency by providing two virtual channels within a 12.5 kHz channel.  For TDMA, the two virtual channels are commonly referred to as “TDMA slots”.  When a 12.5 kHz channel is operating in TDMA mode, the infrastructure is using both slots for outbound signaling.  Depending on how the TDMA channel is being used, radios are instructed to use one or the other slot for inbound signaling (radio to infrastructure) and radios will listen to one or both slots for outbound signaling (infrastructure to radio).

Prior to the development of the TDMA control channel, both FDMA and TDMA trunking traffic channels utilized an FDMA 12.5 kHz control channel.  A new addition to the P25 suite of standards defines a TDMA control channel for P25 trunking operation.  Similar to the FDMA trunking control channel, the TDMA control channel includes an inbound (radio to infrastructure) channel which is used for individual or group service requests for voice, data or supplementary service.  It also includes an outbound (infrastructure to radio) channel which broadcasts system information, control signaling, and provides call assignments.





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